Thursday, August 7, 2014

Selected Readings on Human Health, Disease, and the Environment

The following
are responses and summaries of various readings related to Human Health,
Disease, and the Environment.

Under the Weather:
Temporal and Spatial Scaling

Though climate varies naturally over
time, recent global warming is of great concern. The many parts of an area’s ecology such as
soil fertility, species variability, and organic growth rates and reproductive
cycles vary with changes in altitude and latitude; these differences are known
as the spatial climate gradients. Too
cold nights and winters and too warm days and summers have drastic impact on
the populations and geographic range of disease carriers and can also have an
effect on the organisms of disease as well.
Climate variability taking place over the time frame from biyearly to
every decade is due to atmospheric, oceanic, and cosmological influences, such
as sunspots. These changes can result in
multi-year droughts, monsoons lasting for decades, and vastly different
hurricane activities, which have all been shown to affect productivity of plant
life, likelihood of bird reproduction, and an increase in insect
population. Longer time scales such as
that of the little ice age can cause great population range shifts or possibly
extinction. The recent global warming
has resulted in earlier springs, declines in the populations of birds, mammals,
and amphibians, and a change in geography for butterfly, bird, and marine
invertebrates. While the average
temperature has been increasing globally over the last century, of greater
concern is the extreme temperature increases, higher in mid-day and lower in
mid-night, which has been shown to have a greater impact on animal and plant
species’ population and range. Recently
experimental manipulation has been used in either localized outdoor
environments or in laboratories to analyze what effects climate change could
have on the ecosystem by altering the temperature of soil and air and type and
amount precipitation or combination of the alterations: the growth rates of
plants, invertebrate organism population, plant reproduction, and soil organism
and chemical make-up have all been shown to be affected.

It may be possible through the analysis of how
a disease vector reacts to changes in the environment, to predict what effect
future climate change might have on that same vector. Climate change over long periods of time
should not be used to predict possible ecological behavioral reactions because
there are environmental factors in action other than climate. Many disease vectors are well adapted to
scheduled environmental change such as seasonal cycles or ENSO. Also, socioeconomic changes are likely to be
more significant over decades to centuries, rather than seasonally to annually. Only climate change experiment can provide
the information necessary to prove causation because there may be other factors
involved and the climate change is merely coincidental. Merely because an effect is seen only in a
certain spatial area does not mean that it is caused by change in that
particular region. Experiments are
limited in size and therefore may not be able to predict what may result from
similar climate change over a large area.
These experiments need be focused on the diseases which are more
dependent on climate change than not, such as dengue.

Improved health and human nutrition is a key to putting an
end to poverty. Though, if wealth is
obtained without an improvement in diet, human health and nutrition will
continue to decline. Poor nutrition and
lack of nutritional options are, though not for a complete ignorance or neglect
of the subject, still a major killer throughout the world, especially in the
young and pregnant. The battle has begun
to be fought on two fronts with many developing countries now also fighting
against over nutrition and obesity.
Obesity and malnutrition are together responsible for more than half of
the world’s diseases, with nearly 100 million adults and 20 million children
believed to be obese. Since the 1960s
the staple foods such as cereals, pulses, and starchy roots have been phased
out in many areas having been replaced by foods high in vegetable oils and
sugars, especially in low income nations and the developing world. The decreased availability of staple foods in
the developing countries seems to have gone hand-in-hand with the reduction of
quality in human diets and nutrition. Agriculture
and human health affect one another, though not necessarily equally. The processing which occurs during the
production of food can greatly contribute to poor health, depending on how the
food is being produced and consumed by the end user. Investigations need to be undertaken to find
out what the policies initiated and enforced by agriculture which are causing
these deficiencies are and look for alternative possible policies, perhaps to
be policed by a sector other than agriculture itself.

Organic agriculture makes use of the natural ecological
processes to produce food which is good without the negative effects. Organically grown food is better for use in
seeking good human health and nutrition because it has greater nutritional
quality and quantity, with much less chemical residue left over from
pesticides, herbicides, and fertilizers.
The produce which is grown organically gains nutrients from the soil in
which it grows that would not be obtained by conventional means. Organic produce has a greater density of
nutrients due to its decreased water content, have more iron, magnesium,
vitamin C, and antioxidants, and have a balance of amino acids more in line
with good human health. Organic
livestock are healthier, less likely to contract a disease potentially harmful
to themselves or humans, and have a lower ratio of saturated fat to unsaturated
fat. Organic foods receive less
processing than conventionally produced foods such as, chemicals, irradiation,
additives, and flavors. Organically
produced food does not contain nearly the residues which conventionally produced
food does which can hurt the endocrine or immune system, cause cancer, and
cause sexual reproductive problems even after being well cleaned. The antibiotics which are funneled in to
conventional livestock to prevent disease and promote growth can create resistant
strains in humans. Organic agriculture
is better for the environment, the consumer, the government, the economy, and
the industry. Going completely organic
would likely result in an overall improved health of the population and a great
reduction in the cost of human health.

Readings above may have been drawn from the
following sources:

Six
Modern Plagues and How We are Causing Them, Mark Jerome Walters; Shearwater Books, 2003, ISBN 155963992X